Shorelines: Processes, Features, and Formations

Dr. Ahmad Redaa

2025-04-08

What Are Shorelines?

Wave Formation

Key Wave Parameters

Source: Steven, E. (2015)

Wave Motion

By: Kraaiennest - Own work, CC BY-SA 4.0

What is the Wave Base?

Source: Steven, E. (2015)

What Happens as Waves Approach Shore?

The effect of waves approaching a sandy shore, Source: Steven, E. (2015)

Wave Breaking & Longshore Currents

Waves approaching the shore of Long Beach in Pacific Rim National Park. As the waves (depicted by white lines) approach shore, they are refracted to become more parallel to the beach, and their wavelength decreases, Source: Steven, E. (2015)

Longshore Current Formation:

The generation of a longshore current by waves approaching the shore at an angle. Source: Steven, E. (2015)

Longshore Current: Erosion & Deposition

The movement of particles on a beach as a result of swash and backwash, Source: Steven, E. (2015)

Rip Currents

The formation of rip currents on a beach with strong surf., Source: Steven, E. (2015)

Rip Currents: example

Rip currents on Tunquen Beach in central Chile, Source: Steven, E. (2015)

Landforms Created by Coastal Erosion

Headlands and Bays

Sea Cliffs

Wave-Cut Platform

Sea Caves → Arches → Stacks

Coastal Straightening

Evolution of a straightened coast

Evolution of a straightened coast through the erosion to stacks and arches, sea cliffs, and wave-cut platforms, Source: Steven, E. (2015)

Wave-Cut Platform

A wave-cut platform in bedded sedimentary rock on Gabriola Island, B.C. The wave-eroded surface is submerged at high tide, Source: Steven, E. (2015)

Stacks

A stack on the Juan de Fuca Trail section of the southwestern shore of Vancouver Island. The rock surrounding the stack is part of a wave-cut platform, Source: Steven, E. (2015)

Arch and Stack

Top: An arch in tilted sedimentary rock at the mouth of the Barachois River, Newfoundland, July 2012. Bottom: The same location in June 2013. The arch has collapsed and a small stack remains, Source: Steven, E. (2015)

Landforms Created by Coastal Deposition

Beaches

The components of a sandy marine beach. A berm, the part of a beach that is beyond the reach of high tide, is part of the backshore. The beach face, the part of the beach between low tide and high tide level, includes the swash zone and the foreshore. Beyond the swash zone is the surf zone and beyond that is the breaker zone. Source: Steven, E. (2015)

Spit

The formation of Goose Spit at Comox on Vancouver Island. The sand that makes up Goose Spit is derived from the erosion of Pleistocene Quadra Sand (a thick glaciofluvial sand deposit, as illustrated in the photo on the right). Source: Steven, E. (2015)

Watch this video on YouTube: Spit formation by longshore drift

Baymouth Bar and Tombolo

The formation of Goose Spit at Comox on Vancouver Island. The sand that makes up Goose Spit is derived from the erosion of Pleistocene Quadra Sand (a thick glaciofluvial sand deposit, as illustrated in the photo on the right). Source: Steven, E. (2015)

Baymouth Bar

Tombolo

Barrier Island

A sketch of typical barrier island location on symbolic coasts. Source: Obiefuna et al. (2021)

Watch this video on YouTube: What is a Barrier Island?

Carbonate Reefs

Cross-section through a typical barrier or fringing reef. Source: Steven, E. (2015)